DE202013102671U1 - Thickness adjustment for grinding machines - Google Patents

Abstract

Grinding machine (1) for machining workpieces (2), which are preferably at least partially made of wood, wood composites, plastics, metals and similar materials, comprising: - at least one grinding unit (10) with preferably vertically adjustable grinding device (12) for grinding a Workpiece (2); - A conveying device (5) for conveying the workpiece (2) in a direction of passage (R) by the at least one grinding unit (10); - A control device (100) which is adapted to tune the operation of the at least one grinding unit (10) to a finished dimension desired thickness of the workpiece (2); characterized in that: - the grinding machine (1) further comprises a thickness determination device (30) which is arranged in the direction of passage (R) after the at least one sanding unit (10), and with which a finished actual thickness of the by the at least one sanding unit ( 10) machined workpiece (2) can be determined; and - the control device (100) is further adapted to match the finished dimension actual thickness of the workpiece (2) with the finished dimension desired thickness and to control the operation of the at least one sanding unit (10) such that the finished actual thickness of the finished dimension desired thickness is adjusted.

Description

Field of the invention

The invention relates to a grinding machine for machining workpieces made of wood, wood composites, plastic, metals and similar materials. The invention further relates to a method for grinding a workpiece using the grinding machine according to the invention.

State of the art

A generic grinding machine is for example from the European patent specification with the number EP 0 571 343 A1 known. The grinding machine knows a grinding unit. for grinding a workpiece. The actual grinding process is accomplished within the grinding aggregate by a grinding device. Here, the grinder has the EP 0 571 343 A1 via a belt grinding device. Furthermore, the grinding machine is the EP 0 571 343 A1 characterized by a conveying device which conveys the workpiece by the grinding unit. The grinding unit and the conveying device are controlled by a control device.

The grinding effect is measured here not only from the interaction of grinding unit and conveying device, but also depends on the nature of the workpiece. In particular, the thickness of the processed, d. H. ground workpiece from the raw thickness of the workpiece. In order to achieve a certain grinding effect, it is therefore necessary to adapt the grinding machine and the grinding process to the raw thickness of the workpiece. However, when the grinding machine is operated, for example due to vibrations or due to a varying raw thickness, undesired deviation in the material thicknesses of the machined workpieces can occur, which significantly increases the scrap during the machining of workpieces.

Subject of the invention

The object of the invention is to provide a grinding machine, with the help of the Committee with regard to processed, d. H. sanded workpieces can be reduced. Further, it is an object of the present invention to provide a method which reduces the amount of machined workpieces using a grinding machine.

These objects are achieved by means of a grinding machine according to claim 1. Advantageous embodiments are listed in the dependent claims.

The inventive grinding machine for machining workpieces comprises at least one grinding unit for grinding a workpiece, wherein the at least one grinding unit has at least one preferably vertically adjustable grinding device. The grinding machine further comprises a conveying device for conveying the workpiece in a direction of passage through the at least one grinding unit, and a control device which is adapted to tune the operation of the at least one grinding unit to a finished dimension desired thickness of the workpiece. The term vertical refers to a direction parallel to the thickness direction of the workpiece. The finished target thickness is the desired thickness that a workpiece should have after being processed by the grinder. The conveying direction of the conveying device can be reversible in order to convey a workpiece against the passage direction.

The grinding machine according to the invention is characterized in that it further comprises a thickness-matching device which is arranged in the direction of passage after the at least one grinding unit, wherein the thickness-determining device can determine a finished actual thickness of the workpiece processed by the at least one grinding aggregate. The grinding machine according to the invention is further characterized in that the control device is further adapted to match the finished dimension actual thickness of the workpiece with the finished dimension target thickness, and to control the operation of the at least one grinding unit such that the finished dimension actual thickness of the finished dimension target thickness is adjusted , The finished actual thickness is the thickness that the workpiece actually has after being processed by the grinding machine.

By providing a thickness determination device which determines the finished actual thickness of the machined workpiece and a control device which adjusts this finished actual thickness with the finished dimension desired thickness and controls the operation of the grinding aggregate such that the finished actual thickness of the finished dimension target thickness is adjusted makes it possible to compensate for fluctuations in the operation of the grinding machine and in the nature of the unprocessed workpiece directly, whereby the reject can be reduced. Further, by providing the thickness determining means and the appropriately adjusted controller, adaptation to changing operating conditions can be made directly during operation of the grinding machine without having to stop and rebuild the machine. In addition, the grinding machine according to the invention enables a continuous and complete monitoring of the machined workpieces, whereby a possible faulty production can be detected and corrected immediately.

In a preferred embodiment of the present invention, the grinding machine according to the invention further comprises a second thickness determining device, which is arranged in the direction of passage in front of the at least one grinding unit. In this case, the raw material actual thickness of the unprocessed workpiece can be determined with the second thickness determination device, and the control device is furthermore suitable for matching the raw stock actual thickness of the workpiece to the raw stock target thickness and controlling the operation of the at least one grinding aggregate based on the balance of the raw material. Actual thickness to be controlled with the Rohhaß target thickness such that a thickness of the machined by the at least one grinding unit workpiece is adjusted as possible the finished dimension target thickness. This makes it possible to adapt the grinding process to the thickness of the workpiece already before starting the machining of the workpiece. This pre-adjustment can further reduce the scrap. The raw material actual thickness is the actual thickness of the workpiece before it is processed by the grinding machine. The raw gauge target thickness is the desired thickness of the workpiece before it is machined.

It is preferably provided that the control device is also suitable for adapting the finished dimension actual thickness of the workpiece to the finished dimension desired thickness and the adaptation based on the comparison of the raw tube actual thickness with the raw dimension target thickness by outputting a total grinding depth to the to accomplish at least one grinding aggregate. This makes it possible to make the thickness adjustment as homogeneous as possible, which further increases the machining quality of the workpiece and reduces waste. The grinding depth can preferably be accomplished by a method of the grinding device (s) together or individually in the vertical direction or by a change in the contact pressure with which the grinding device (s) are applied by the grinding units to the workpiece.

In a preferred embodiment of the present invention, the grinding machine is further characterized by comprising a top grinding grinding aggregate which grinds the workpiece at the top of the workpiece and a bottom grinding grinding aggregate which grinds the workpiece at the bottom of the workpiece. Both grinding units, the abrasive grinding machine from above and the abrasive grinding machine from below, have a preferably vertically adjustable grinding device. In this context, the term "top" refers to a position above the workpiece, which is conveyed by the conveyor through the grinding unit. The abrading grinding unit is thus arranged above the workpiece and performs a grinding operation at the top of the workpiece. The same applies in this context for the term "bottom": The grinding from below grinding unit is arranged below the conveyed by the conveyor by the grinding unit workpiece. The sanding grinding unit grinds the workpiece on its underside.

Furthermore, it is provided in particular that the total grinding depth is divided in equal parts to a grinding depth of the abrasive grinding machine from above and a grinding depth of the abrasive grinding machine from below. As a result, even when machining the workpiece on the top and bottom, a uniform thickness adjustment can be made, which has both beneficial to the processing quality, as well as the avoidance of waste. In particular, stresses that result from machining in the workpiece can be reduced or not introduced. In addition, it can be ensured that the core area of the workpiece is not affected by the machining.

The thickness determination device and the second thickness determination device preferably each have at least one sensor pair with an upper sensor, a lower sensor and an evaluation device. In this case, the lower sensor is arranged in relation to the conveyed by the conveying device workpiece such that it is located below the workpiece. The upper sensor is then arranged to be in a direction parallel to the thickness direction of the workpiece above the workpiece and above the lower sensor. Here, the upper and lower sensors occupy a predetermined distance from each other. Upper and lower sensors are preferably laser optics sensors.

Preferably, the upper sensor of a sensor pair is suitable for determining an upper distance from the workpiece, and the lower sensor of a sensor pair is suitable for determining a lower distance from the workpiece. Each evaluation device of a sensor pair is also suitable, based on the pair of sensors, to determine a single finished dimension actual thickness or a single raw dimension actual thickness of the workpiece starting from the predetermined distance, the upper distance and the lower distance. The thickness of the workpiece preferably results from the difference between the predetermined distance minus the upper distance minus the lower distance.

Preferably, the control device is also suitable for determining an average value from the individual finished dimension actual thicknesses and / or from the individual raw stock actual thicknesses in order to obtain the finished dimension actual thickness and / or the raw gauge actual thickness.

In one embodiment of the present invention, the thickness-determining device and the second thickness-determining device each have n sensor pairs which are distributed uniformly over the working width of the at least one grinding aggregate. In this case, n is preferably three. This makes it possible to grasp the raw stock actual thickness of the workpiece and / or the finished actual thickness of the workpiece over the entire width of the workpiece, which reduces the susceptibility to errors and thus the rejection of the system.

In one development of the invention, the sensor pairs can be arranged horizontally within the thickness determination device and the second thickness determination device, which makes it possible to adapt the sensor position to the working width.

In one embodiment of the present invention, each sensor has a measuring range, and the evaluating devices of the sensor pairs are suitable for determining a single finished actual thickness or a single raw dimension actual thickness of the workpiece, if both the upper distance and the lower distance smaller or equal to the measuring range. Thus, it is irrelevant whether only one sensor pair detects a workpiece or all, and the error rate of the grinding machine according to the invention can be further reduced. In particular, there is no erroneous output of a single finished actual thickness or a single raw dimension actual thickness, if no workpiece between the upper and lower sensor of a pair of sensors.

Preferably, the grinding device (s) of the grinding machine according to the invention are / are oscillating grinding devices, a belt grinding device, disc brushes or grinding rollers.

In an embodiment of the present invention, the grinding machine further comprises a display device capable of continuously displaying the raw stock actual thickness and the finished actual thickness. Further, the display device is adapted to display time average values of the raw stock actual thickness and the finished actual thickness based on the time average of the raw stock actual thickness and the finished actual thickness over a predetermined time interval. In addition, the display device is adapted to display a message that causes a user to perform an action when the finished actual thickness deviates by a predetermined amount from the finished target thickness and / or the finished actual thickness over a predetermined time interval by a predetermined amount of deviates from the finished dimension target thickness. This not only makes it possible to track the time course of the raw stock actual thickness and the finished actual thickness and to carry out a continuous quality control, it also makes it possible to induce the user of the grinding machine in the event of a malfunction to early intervention.

For precisely this reason, according to a further development, the grinding machine may further comprise a warning device capable of displaying a warning when the finished dimension actual thickness deviates from the finished dimension target thickness by a predetermined amount and / or the finished actual thickness over a predetermined time interval deviates a predetermined amount from the finished dimension target thickness.

A method using the aforementioned grinding machine will be described. The method comprises the steps of: determining a finished dimension actual thickness of the workpiece processed by the at least one sanding unit by the thickness determination device; Matching the finished dimension actual thickness of the workpiece with the finished dimension desired thickness by the control device; and controlling the operation of the at least one grinding aggregate by the control device in such a way that the finished dimension actual thickness as a whole is adapted to the finished dimension setpoint thickness. Thereby, it is possible to provide a method which allows a continuous thickness control of a ground workpiece, adapts the operation of the grinding units accordingly and thus reduces the rejects.

The particular advantage of the method lies in the fact that with the exception of the thickness determination device and an adaptation of the control device can be made of the facilities of conventional grinding machines. This makes it possible to reduce the waste in the machining of workpieces cost and uncomplicated.

According to a preferred embodiment, the method further comprises the steps of: determining a raw-material actual thickness of the unprocessed workpiece by a second thickness-determining device; Balancing the raw stock actual thickness of the workpiece with the finished dimension target thickness; and controlling the operation of the at least one grinding aggregate by the control device such that a thickness of the workpiece processed by the at least one grinding aggregate is adjusted overall as far as possible to the finished dimension desired thickness. Through these steps, it is possible to make an adjustment of the grinding machine to the raw material actual thickness of the workpiece already before the beginning of the grinding process. As a result, variances in the raw material actual thicknesses of the workpiece can already be compensated in advance, whereby the rejects can be further reduced.

The method is further preferably characterized in that an overall grinding depth the at least one grinding unit for adjusting the finished dimension actual thickness of the workpieces to the finished dimension target thickness and for adjusting based on the comparison of the raw material actual thickness is output with the raw dimension target thickness. In this case, the total grinding depth is preferably divided equally into the grinding depth of the abrading grinding aggregate and the grinding depth of the abrading grinding aggregate. As a result, the adaptation of the finished dimension actual thickness and the raw stock actual thickness of the workpiece to the finished dimension desired thickness can be effected uniformly from above and from below, whereby the grinding result is further improved.

The method is preferably characterized in that average values are formed from the individual finished-dimension actual thicknesses obtained from individual sensor pairs and / or the individual raw-material actual thicknesses obtained from individual sensor pairs in order to obtain the final dimension actual thickness and / or the raw dimension actual thickness.

Brief description of the figures

1 shows a schematic view of the grinding machine according to the present invention.

2 shows a sectional view of the grinding units according to the present invention.

3 Fig. 10 shows a front view of the thickness-determining device according to the present invention.

4 Fig. 2 shows a schematic side view of the thickness determination device according to the present invention. The distances determined by the sensors and the sensor distance are shown.

Detailed description of preferred embodiments

In 1 is a grinder 1 according to an embodiment of the present invention shown in a schematic sectional view. Other modifications mentioned in this context can each be combined with each other to form new embodiments.

Here are the essential elements of the grinding machine 1 the grinding units 10 , the promotion facility 5 and the controller 100 , Furthermore, the grinding machine 1 be mounted on a supporting device, not shown in this view.

The promotion facility 5 promotes a workpiece 2 in a direction of passage R. This causes the workpiece 2 through the grinding units 10 promoted. In general, the grinder can 1 several sanding units 10 exhibit. The grinding units 10 have preferably vertically adjustable grinding devices 12 , These grinding devices 12 may include an oscillating grinder, a disc brush, or an abrasive roller. It may be advantageous if the conveying device 5 is reversible in its conveying direction, thus a workpiece 2 to promote against the passage direction R. This can not only be of concern in case of malfunctioning of the grinding machine but can also be used to obtain special grinding results.

According to one embodiment of the present invention, first a thickness determining device 30 in the direction of flow R after the grinding units 10 arranged. The thickness determination device 30 is suitable, a finished actual thickness of the by the grinding units 10 machined workpiece 2 to determine. This finished actual thickness is in the control device 100 entered.

The control device 100 is suitable to match the finished actual thickness with a finished dimension target thickness. The finished dimension target thickness corresponds to the desired thickness of the workpiece 2 , this after the grinding process by the grinding units 10 should have. Based on the comparison of the finished actual thickness with the finished dimension target thickness controls the controller 100 the grinding units 10 ,

In this case, the control takes place in such a way that the finished dimension actual thickness of the finished dimension target thickness is adjusted. The adaptation can by means of a vertical process of grinding equipment 12 , a change in the conveying speed and / or a change in the contact pressure with which the grinding devices 12 to the workpiece 2 are created, done.

The following is with reference to 3 the thickness determination device 30 explained in more detail. As in 3 shown has the thickness determination device 30 according to an embodiment over several sensor pairs 33 , each one a lower sensor 32 and an upper sensor 31 include. Furthermore, each sensor pair has 33 via an evaluation unit 34 , The upper sensor 31 is in relation to the workpiece 2 at a given distance just above the lower sensor 32 arranged so that the workpiece 2 can be conveyed through between the upper and lower sensor. The specified distance between the upper sensor 31 and lower sensor 32 a sensor pair 33 is parallel to the thickness direction of the workpiece 2 , In general, the sensors can 31 . 32 be of the most different kind. In one embodiment of the present invention are the sensors 31 . 32 Laser optics sensors.

In general, the thickness determination device has 30 over several sensor pairs 33 , which are arranged uniformly over the working width b of the grinding machines. Preferred, and how 3 shown has the thickness determination device 30 over three sensor pairs 33 , Furthermore, it can be provided, the sensor pairs 33 To arrange horizontally displaceable in the thickness determining device, whereby for example an adaptation to the working width of the grinding units can be made.

As mentioned, the upper sensor is located 31 and the bottom sensor 32 in a (known) predetermined distance. Is there a workpiece? 2 between the upper sensor 31 and the lower sensor 32 , the lower sensor determines 32 a lower distance (a distance from the lower sensor 32 to the bottom of the workpiece 2 ) and the upper sensor 31 an upper distance (a distance from the upper sensor 31 to the top of the workpiece 2 ). The upper distance and the lower distance are in the evaluation device 34 of the sensor pair 33 enter. This evaluation device 34 determines, based on the given distance, the upper distance, and the lower distance, a single finished actual thickness of the workpiece 2 , This results in the individual finished dimension actual thickness of the workpiece 2 from the difference between the given distance minus the upper distance minus the lower distance. The from each sensor pair 33 certain individual finished actual thicknesses of the workpiece 2 are from the evaluation devices 34 in the control device 100 entered. This is calculated from these individual finished dimension actual thicknesses of the workpiece 2 by arithmetic averaging the finished dimension actual thickness of the workpiece 2 , This finished actual thickness of the workpiece 2 is from the controller 100 adjusted to the finished dimension target thickness. This information is then, as mentioned above, to control the grinding units 10 used.

Every sensor 31 . 32 also has a measuring range, and the evaluation devices 34 are suitable, only a single thickness of the workpiece 2 to the controller 100 output when both the determined lower distance, as well as the determined upper distance respectively within the measuring ranges of the lower sensor 32 and the upper sensor 31 lie. This ensures that there is firstly no malfunction of the thickness determination device 30 comes, and second, that only a single thickness in the controller 100 is entered when a workpiece 2 between the upper sensors 31 and the lower sensors 32 a sensor pair 33 lies.

How out 1 As can be seen, the grinding machine of the present invention can not only have a thickness-determining device 30 have, in the direction of passage of the grinding units 10 rather, in a further embodiment, rather, via a second thickness determining device 40 have, in the direction of R before the grinding aggregates 10 lies. With this second thickness determination device 40 , Incidentally, according to the thickness determination device 30 is constructed, it is now possible, one or more individual raw tube actual thicknesses of the workpiece 2 to determine before the workpiece 2 through the grinding units 10 is processed.

These raw meter actual thicknesses are then in the control device 100 entered, which is suitable, from an average value of the raw material actual thickness of the workpiece 2 to determine and to match this with the Rohhmaß-Solldicke. The control device 100 is also set up, the operation of the grinding units 10 based on the balance of the raw dimension actual and target thicknesses to control such that a thickness of the by the grinding units 10 machined workpiece 2 overall as far as the finished dimension target thickness corresponds.

The raw dimension actual thickness is calculated analogously to the calculation of the finished dimension actual thickness. First, each sensor pair is determined 33 in each case a single raw stock actual thickness, which is then averaged by the control device 100 be converted into the raw material actual thickness. The individual raw dimension actual thicknesses are in each case from the difference between the predetermined distance of a sensor pair 33 minus the upper distance minus the lower distance. The sensors also show the raw dimension-actual thickness determination 31 . 32 a measuring range, and the evaluation devices 34 are suitable, only a single thickness of the workpiece 2 to the controller 100 output when both the determined lower distance and the determined upper distance respectively within the measuring ranges of the lower sensor 32 and the upper sensor 31 lie.

When using multiple sanding units 10 it is also advantageous if the control device 100 calculated from the discrepancy between finished actual thickness and finished dimension target thickness or raw stock actual thickness and raw target nominal thickness a total grinding depth. This total grinding depth can then advantageously in equal parts to the several grinding units 10 be split.

When machining workpieces 2 By grinding, according to a preferred embodiment, it may further be advantageous if, as in FIG 2 shown a sanding unit 10 a sanding grinding unit from above 10a is while the other sanding unit 10 one from below grinding grinding unit 10b is. The sanding grinding unit from above 10a has, as in 2 shown via vertically adjustable grinding equipment 12 that is the top of the workpiece 2 with respect to the direction of passage R of the workpiece 2 are held up from above. The sanding grinding unit from below 10b has vertically adjustable grinding equipment 12 that the workpiece 2 relative to the passage direction R are held against the underside. Consequently, the sanding abrading grinding unit grinds 10a the workpiece 2 at the top and the bottom grinding grinding unit 10b grinds the workpiece 2 at the bottom. The term "vertically adjustable" refers to a displacement of the grinding devices 12 in the thickness direction of the workpiece 2 and / or a change in the contact pressure with which the grinding devices 12 the workpiece 2 are opposed, whereby the grinding depth can be adjusted. Be as in 2 shown, a top grinding sanding unit 10a and a bottom grinding grinding unit 10b combined, it is advantageous if the total grinding depth in equal parts on the abrasive grinding from above 10a and the bottom grinding grinding unit 10b is split. As a result, the deviations determined, or the corrections required in the grinding depth, can be uniformly distributed over the grinding depth of the two grinding units, as a result of which a uniform removal can be achieved on both sides.

Furthermore, the grinding machine 1 furthermore a display device 200 exhibit. This is particularly suitable for continuously displaying the raw-material actual thickness and the final-dimension actual thickness and also calculating and displaying various time average values of the raw-material actual thickness and the finished-actual thickness based on the time average of both values over a predetermined time interval. Furthermore, the display device 200 be able to indicate a message that causes a user to perform an action when the finished actual thickness deviates by a predetermined amount from the finished target thickness and / or the finished actual thickness over a predetermined time interval by a predetermined amount from the finished target thickness differs. For precisely this reason, according to a further development, the grinding machine may further comprise a warning device which is suitable for issuing a warning in the aforementioned case, which preferably takes place acoustically and / or optically.

In operation of the grinding machine 1 This results in the following procedure: First, a determination of the finished dimension-actual thickness of the machined workpiece 2 using the thickness determination device 30 and optionally determining a raw gauge actual thickness of the unprocessed workpiece 2 using the second thickness determining device 40 , The thus determined finished actual thickness of the workpiece 2 is through the control device 100 Adjusted with the finished dimension target thickness, as well as this is possibly the Rohhmass actual thickness of the workpiece 2 aligned with the raw target nominal thickness. These adjustments are the basis for controlling the operation of the grinding units 10 by the control device 100 in such a way that the finished dimension actual thickness as a whole is adapted to the finished dimension nominal thickness.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0571343 A1 [0002, 0002, 0002]

Claims (13)

Grinding machine ( 1 ) for machining workpieces ( 2 ), which are preferably at least partially made of wood, wood composites, plastics, metals and similar materials, comprising: - at least one grinding aggregate ( 10 ) with preferably vertically adjustable grinding device ( 12 ), for grinding a workpiece ( 2 ); - a funding scheme ( 5 ) for conveying the workpiece ( 2 ) in a passage direction (R) through the at least one sanding unit ( 10 ); A control device ( 100 ) suitable for controlling the operation of the at least one grinding aggregate ( 10 ) to a finished dimension desired thickness of the workpiece ( 2 ) to vote; characterized in that: - the grinding machine ( 1 ) further comprises a thickness determining device ( 30 ), which in the direction of passage (R) after the at least one grinding unit ( 10 ), and with which a finished actual thickness of the by the at least one grinding aggregate ( 10 ) machined workpiece ( 2 ) can be determined; and - the control device ( 100 ), is also suitable for the finished actual thickness of the workpiece ( 2 ) and the operation of the at least one sanding unit ( 10 ) in such a way that the finished dimension actual thickness of the finished dimension target thickness is adjusted. Grinding machine ( 1 ) for machining workpieces ( 2 ) according to claim 1, further comprising a second thickness determining device ( 40 ), which in the direction of passage (R) in front of the at least one sanding unit ( 10 ), wherein - with the second thickness determination device ( 40 ) a raw gauge actual thickness of the unprocessed workpiece ( 2 ) can be determined; and - the control device ( 100 ) is also adapted to the raw material actual thickness of the workpiece ( 2 ) with a raw gauge target thickness, and based thereon the operation of the at least one grinding aggregate ( 10 ) such that a thickness of the machined workpiece ( 2 ) is adjusted as far as possible to the finished dimension target thickness. Grinding machine ( 1 ) for machining workpieces ( 2 ), wherein the control device ( 100 ), the adaptation of the finished dimension actual thickness of the workpiece ( 2 ) to the finished dimension target thickness and the adjustment based on the comparison of the raw material actual thickness with the raw target nominal thickness by outputting a total grinding depth to the at least one grinding aggregate ( 10 ) to accomplish. Grinding machine ( 1 ) for machining workpieces ( 2 ) according to one of the preceding claims, wherein the grinding machine ( 1 ) characterized in that it comprises: a sanding abrading unit ( 10a ), preferably with a vertically adjustable grinding device ( 12 ), which grinds the workpiece at the top of the workpiece and a sanding from below grinding aggregate ( 10b ), preferably with a vertically adjustable grinding device ( 12 ), which grinds the workpiece on the underside of the workpiece has. Grinding machine ( 1 ) for machining workpieces ( 2 ) according to claim 4, wherein the total grinding depth equals to a grinding depth of the abrading grinding aggregate ( 10a ) and a grinding depth of the abrading grinding unit ( 10b ) is divided. Grinding machine ( 1 ) for machining workpieces ( 2 ) according to one of the preceding claims, wherein the thickness determining device ( 30 ) and the second thickness determining device ( 40 ) at least one sensor pair ( 33 ) with an upper sensor ( 31 ), preferably a laser optics sensor, a lower sensor ( 32 ), preferably a laser optical sensor, and an evaluation device ( 34 ), wherein, with respect to the transported workpiece ( 2 ), a lower sensor ( 32 ) is arranged so that it is located below the workpiece and an upper sensor ( 31 ) above the workpiece ( 2 ) and the lower sensor ( 32 ) is at a predetermined distance from the lower sensor. Grinding machine ( 1 ) for machining workpieces ( 2 ) according to claim 6, wherein the upper sensor ( 31 ) of a sensor pair ( 33 ) is an upper distance to the workpiece ( 2 ), the lower sensor ( 32 ) of a sensor pair ( 33 ) is suitable, a lower distance to the workpiece ( 2 ), and the evaluation device ( 34 ) of a sensor pair ( 33 ), a single final finished actual thickness or a single raw stock actual thickness of the workpiece ( 2 ) from the given distance, the upper distance and the lower distance. Grinding machine ( 1 ) for machining workpieces ( 2 ) according to claim 7, wherein the control device ( 100 ) is also suitable to determine an average value of the individual finished dimension actual thicknesses and / or the individual raw gauge actual thicknesses. Grinding machine ( 1 ) for machining workpieces ( 2 ) according to one of claims 6, 7 or 8, wherein the thickness determining device ( 30 ) and the second thickness determining device ( 40 ) each n sensor pairs ( 33 ) uniformly over the working width b of the at least one grinding aggregate ( 10 ), where n is preferably 3. Grinding machine ( 1 ) for machining workpieces ( 2 ) according to one of claims 6 to 9, in which each sensor ( 31 . 32 ) has a measuring range and the evaluation devices ( 34 ), only a single finished actual thickness or a single raw material actual thickness of the workpiece ( 2 ), if both the upper distance and the lower distance are less than or equal to the measuring range. Grinding machine ( 1 ) for machining workpieces ( 2 ) according to one of the preceding claims, in which the grinding device ( 12 ) is an oscillating grinder, a belt grinder, a disc brush or an abrasive roller. Grinding machine ( 1 ) for machining workpieces ( 2 ) according to one of the preceding claims, further comprising a display device ( 200 ), which is capable of: - continuously displaying the raw-material actual thickness and the finished-size actual thickness; - To display the time average values of the raw-material actual thickness and the finished-actual thickness based on the time average of the raw-material actual thickness and the finished-actual thickness over a predetermined time interval; and to display a message that causes a user to perform an action when the finished actual thickness deviates from the finished target desired thickness by a predetermined amount and / or the finished actual thickness over a predetermined time interval by a predetermined amount from the finished target desired thickness differs. Grinding machine ( 1 ) for machining workpieces ( 2 ) according to one of the preceding claims, further comprising a warning device, which indicates a warning when the finished dimension actual thickness deviates by a predetermined amount from the finished dimension target thickness and / or the finished dimension actual thickness over a predetermined time interval by a predetermined amount of the Finished dimension target thickness deviates.

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